Windows Explorer keeps shutting down, restarting

I'm somewhat experienced with computers, and I've never had this happen before. Just about every time I close a program window, Windows Explorer will shut down, then restart. Here's my HijackThis LogFile:

Logfile of HijackThis v1.99.1
Scan saved at 3:28:51 PM, on 8/6/2008
Platform: Unknown Windows (WinNT 6.00.1904)
MSIE: Internet Explorer v7.00 (7.00.6000.16681)

Running processes:
C:\Windows\system32\Dwm.exe
C:\Windows\system32\taskeng.exe
C:\Program Files\Windows Defender\MSASCui.exe
C:\Windows\System32\hkcmd.exe
C:\Windows\System32\igfxpers.exe
C:\Program Files\Intel\Intel Matrix Storage Manager\IAAnotif.exe
C:\Windows\sttray.exe
C:\Program Files\Synaptics\SynTP\SynTPEnh.exe
C:\Program Files\Camera Assistant Software for Gateway\traybar.exe
C:\Program Files\Spare Backup\SpareBackup.exe
C:\Windows\system32\igfxsrvc.exe
C:\Program Files\AVG\AVG8\avgtray.exe
C:\Windows\System32\rundll32.exe
C:\Windows\ehome\ehtray.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\Program Files\Windows Sidebar\sidebar.exe
C:\Program Files\Spybot - Search & Destroy\TeaTimer.exe
C:\Windows\ehome\ehmsas.exe
C:\Program Files\Camera Assistant Software for Gateway\CEC_MAIN.exe
C:\Windows\Explorer.EXE
C:\Program Files\Mozilla Firefox\firefox.exe
C:\Program Files\HijackThis\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.gateway.com/g/startpage.html?Ch=Retail&SubCH=BB&Br=GTW&Loc=ENG_US&Sys=PTB&M=M-6750
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://www.gateway.com/g/startpage.html?Ch=Retail&SubCH=BB&Br=GTW&Loc=ENG_US&Sys=PTB&M=M-6750
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://go.microsoft.com/fwlink/?LinkId=54896
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.gateway.com/g/startpage.html?Ch=Retail&SubCH=BB&Br=GTW&Loc=ENG_US&Sys=PTB&M=M-6750
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant = http://www.gateway.com/g/sidepanel.html?Ch=Retail&SubCH=BB&Br=GTW&Loc=ENG_US&Sys=PTB&M=M-6750
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,CustomizeSearch =
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName =
R3 - URLSearchHook: Yahoo! Toolbar - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\Program Files\Yahoo!\Companion\Installs\cpn\yt.dll
O1 - Hosts: ::1 localhost
O2 - BHO: Yahoo! Toolbar Helper - {02478D38-C3F9-4EFB-9B51-7695ECA05670} - C:\Program Files\Yahoo!\Companion\Installs\cpn\yt.dll
O2 - BHO: Adobe PDF Reader Link Helper - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelper.dll
O2 - BHO: bannerstyles browser optimizer - {164595ab-94bd-98ed-8fdb-88bc408afd5d} - C:\Windows\system32\ircxbqqegyg.dll
O2 - BHO: BitComet Helper - {39F7E362-828A-4B5A-BCAF-5B79BFDFEA60} - C:\Program Files\BitComet\tools\BitCometBHO_1.2.2.28.dll
O2 - BHO: AVG Safe Search - {3CA2F312-6F6E-4B53-A66E-4E65E497C8C0} - C:\Program Files\AVG\AVG8\avgssie.dll
O2 - BHO: Spybot-S&D IE Protection - {53707962-6F74-2D53-2644-206D7942484F} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O2 - BHO: (no name) - {602ADB0E-4AFF-4217-8AA1-95DAC4DFA408} - (no file)
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre1.6.0_01\bin\ssv.dll
O2 - BHO: (no name) - {7E853D72-626A-48EC-A868-BA8D5E23E045} - (no file)
O2 - BHO: CBrowserHelperObject Object - {CA6319C0-31B7-401E-A518-A07C3DB8F777} - c:\windows\system32\BAE.dll
O3 - Toolbar: (no name) - {7FEBEFE3-6B19-4349-98D2-FFB09D4B49CA} - (no file)

BTW, I use Windows Vista if that helps. Thanks in advance!